Adds an isCancelling flag to AbstractListReporter so the live status panel
stops re-rendering while the cancel confirmation prompt is on screen, and
resumes when the prompt closes.

- onCancelPromptShown clears the panel and raises the flag.
- onCancelPromptHidden lowers the flag and repaints; runs on both confirm
  and decline so live updates resume during the cancellation drain.
- _printSummary and onStreamLogs short-circuit while the flag is up.
- _clearSummary becomes a no-op when there is nothing to erase, preserving
  the clear/print invariant if a guard skips the paired _printSummary.

PQueue.pause() does not interrupt an in-flight handler. A CHECK_INPROGRESS
handler that started before SIGINT could still emit and trigger a panel
re-render right under the cancel prompt, producing spurious project-tree
output.

- Emit CANCEL_PROMPT_SHOWN before queue.pause(); EventEmitter.emit is
  synchronous so reporters set their flag before any pending handler can
  render.
- Emit CANCEL_PROMPT_HIDDEN after the prompt resolves on both confirm and
  decline, restoring live updates.
- On confirm, print 'Cancelling test session...' so the user sees feedback
  while the backend cancellation completes.
- Always queue.start() after the prompt: drains MQTT results so
  allChecksFinished can resolve on confirm, resumes normal flow on decline.
- Use printLn instead of raw process.stdout.write to match the rest of the
  CLI.

Wires the runner's CANCEL_PROMPT_SHOWN and CANCEL_PROMPT_HIDDEN events to
each reporter for the test, pw-test, and trigger commands.

Covers happy paths (clear-then-repaint, normal render before/after the
prompt) and edge cases (empty _clearString no-op, double prompt-shown
idempotency, prompt-hidden without prior prompt-shown, suppression of
_printSummary and onStreamLogs while cancelling).

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

The interactive confirmation prompt on Ctrl+C broke on Windows due to
cmd.exe's competing "Terminate batch job" dialog and the `when-exit`
transitive dependency (conf → atomically → when-exit) preempting the
SIGINT handler.

Now Ctrl+C always cancels immediately and suggests --detach for keeping
checks running. Uses prependListener to run before when-exit's handler.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

…ve prompt

The interactive confirmation prompt on Ctrl+C conflicted with cmd.exe's
"Terminate batch job" prompt on Windows, and a transitive dependency
(when-exit via conf → atomically) preempted the SIGINT handler by
re-raising SIGINT, which is a hard kill on Windows.

Replace the prompt with immediate cancellation: first Ctrl+C emits
CANCEL and shows a message suggesting --detach, second Ctrl+C force
exits. The cancellation message is rendered by the reporter as part of
its live summary panel so it doesn't get overwritten. Pre-existing
SIGINT listeners are removed during the run and restored afterward to
prevent when-exit from terminating the process.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Ctrl+C with --detach now shows "Checks will continue running in the
cloud." before exiting, instead of silently terminating.

Also refactors the SIGINT handler setup: both detach and non-detach
modes share the same when-exit listener removal and registration code,
with the mode-specific behavior inside the handler body.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

The cancel endpoint returns 403 when the account doesn't have the
feature flag set. Silently ignore it since cancellation is best-effort.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>